Programa de Pós-graduação em Odontologia

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Navegando Programa de Pós-graduação em Odontologia por Autor "Almeida, Letícia Nunes de"

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    Desempenho biomecânico de novos retentores intrarradiculares em dentes com ou sem férula
    (Universidade Federal de Goiás, 2020-02-28) Almeida, Letícia Nunes de; Fonseca, Rodrigo Borges; http://lattes.cnpq.br/8629552867290605; Fonseca, Rodrigo Borges; Lopes, Lawrence Gonzaga; Barata, Terezinha de Jesus Esteves; Kasuya, Amanda Vessoni Barbosa; Favarão, Isabella Negro
    The aim of this study was to evaluate the influence of intrarradicular post system and the amount of coronary remnant (ferrule) on maximal fracture load, fracture pattern and stress distribution of endodontically treated teeth. Eight experimental groups were created: Pf-0 e Pf-2 - glass fiber post (GFP) no. 3 in teeth with and without ferrule respectively; GFP no. 1 relined with experimental composite (EC) with and without ferrule respectively; EC-0 and EC-2 - custom post made with the experimental composite (EC) with and without ferrule respectively, CAD-0 e CAD-2 - custom milled post with and without ferrule respectively. The EC was composed of 22.5 wt% of methacrylate resin (Bis-GMA, TEGDMA, Bis-EMA), 30% of glass fibers and 47.5% of filler particles. After endodontic treatment, post cementation and crowns with composite resin, the teeth were tested to verify the maximum fracture load (n = 10) in a universal testing machine (Instron 5965) a 0.5 mm/min. Subsequently, the fracture pattern was analyzed and stress distribution was evaluated by the finite element method using the modified von Mises criterion (MSC Marc & Mentat). The maximum fracture load results were subjected to factor analysis, and subsequently Kolmogorov-Smirnov, ANOVA, Tukey and T-Test for comparison between groups (α = 0.05). Interaction was observed between the factors under study (p = 0.046), and ANOVA and Tukey showed a statistically significant difference between the groups (p = 0.001). EC-0 (752.81N) and CAD-0 (728.84N) were similar and superior Pr-0 (545.16) and Pf-0 (498.01N). In ferrule groups, all retainers were similar (p>0.05) Pf-2 (791.85), Pr-2 (699.1), EC-2 (822,81), CAD-2 (779.89). Pf-0 showed a greater number of non-repairable failures and the Pr-2 posts promoted a greater number of favorable failures. Groups without ferrule showed higher number of non-repairable failures. The posts made with EC showed lower stress concentration and the posts made by CAD / CAM technique, the highest stress concentration. Retainer type and presence of ferrule influence on maximal load, fracture pattern and stress distribution of endodontically treated teeth. CE custom posts promote higher maximum fracture load and more favorable stress distribution.
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    Efeito do pré-aquecimento e da pós-polimerização nas propriedades mecânicas e grau de conversão de um compósito experimental reforçado com fibra de vidro
    (Universidade Federal de Goiás, 2016-02-25) Almeida, Letícia Nunes de; Fonseca, Rodrigo Borges; http://buscatextual.cnpq.br/buscatextual/visualizacv.do?metodo=apresentar&id=K4770435A0; Fonseca, Rodrigo Borges; Souza, João Batista de; Menezes, Murilo de Souza
    The pre-heating and post-curing can improve the mechanical properties of composites, even though there be no studies of fiber reinforced composites. The aim of this study was to evaluate the effect of pre-heating and post-curing autoclave and microwave in flexural strength (FS), diametral tensile strength (DTS), knoop microhardness (KHN) and degree of conversion (DC) of a experimental fiber- reinfoced composite. The experimental material was prepared with 30% glass fibers (3 mm), 22.5% of the resin matrix (40/60 Bis-GMA / TEGDMA) and 47.5% barium silicate particles. Six experimental groups were created by the interaction between the factors under study: heating, on two levels (without heating and heating at 60°C) and post-curing in 3 levels (conventional curing without post-curing, autoclave (120°C for 15 minutes) and microwaves (540 W for 5 minutes) The groups were: F - curing at 1500 mW/cm2 for 40 seconds; F + M - curing and post- polymerization in microwave; F + A - curing and post-curing in an autoclave , AQ + F - the composite heating prior to curing, AQ + F + M - heating prior to curing and post-curing in microwave;. AQ + F + A - heating prior to curing and post-curing and autoclave heating was conducted digital oven for 5 minutes at 60°C. Ten samples of the RF dimensions 25 x 2 x 2 mm and DTS in dimensions of 3 x 6 mm were tested in a universal testing machine Instron 5965, 0.5 mm/min. the KHN test was performed on samples of 3 x 6 mm with a load of 50 g for 30 sec, totaling 50 indentations per group. GC was obtained by Spectroscopy Fourier Transform Infrared (FTIR) on 5 samples. Data were analyzed by a factorial 2x3 and general linear model ANOVA and Tukey tests (α = 0.05). Factor analysis showed significant interaction between the factors just for RTD (p = 0.0001); preheating was significant factor for RF (p = 0.0001), RTD (p = 0.020) and KHN (p = 0.0001); post-curing factor for KHN was significant (p = 0.0001). ANOVA and Tukey tests showed statistically significant differences between groups for DTS (p = 0.001: AQ + F ≥ AQ + F + M = F + A = AQ + F + A = F + M ≥ F), FS (p = 0.016: AQ + F + M ≥ AQ + F + A + F = AQ = AQ + A + M ≥ F ≥ F) and KHN (p = 0.0001: AQ + F + M ≥ AQ + A + F = F = F + A + M ≥ F ≥ M + AQ). GC results showed no statistically significant difference. Through the Pearson correlation coefficient was observed significant positive correlation between the GC and RTD (r = 0.473, p = 0.008) and between DTS and FS (r = 0.263, p = 0.042). The pre-heating and post- polymerization were shown to be favorable to promote better mechanical properties of fiber reinforced composite by studied, specific for each property being analyzed.